This invention relates in general to respirators and in particular to a new and useful respirator mask control valve.
Such a respirator mask with positive pressure in the interior of the mask is already known from German Patent application No. P 32 45 717.
In compressed gas respirators with positive pressure in the mask it is ensured that a positive pressure prevails in the mask during use both in the exhaling and in the inhaling phase. This positive pressure prevents, under all circumstances, possibly harmful ambient atmosphere from getting into the mask during use. In them, gas can flow only from the interior outwardly if leaks develop. In these respirators, however, the difficulties must be overcome which result from the fact that when use is ended and the mask is taken off, that is, with the opening of the respiratory cycle, the respiratory gas reservoirs must be closed or the operation of the lung motor switched, to avoid discharge of respiratory gas and hence shortening of the utilization time.
From German OS No. 30 38 100 equipping a respirator mask with a lung controlled valve is known with which a positive pressure is created and maintained in the interior of the mask. The valve comprises in a valve housing, between a breathing chamber discharging before the respiratory organs of the user and an outer chamber connected with the outside atmosphere, a pressure chamber connected with both chambers through a valve for each. With this pressure chamber a positive pressure is created in the breathing chamber and hence in the interior of the mask both during inhalation and during exhalation. To this end, a wall portion of the pressure chamber is movably connected with the inner wall of the valve housing via a control membrane. A respiratory gas inlet valve of the mask is actuated through an actuating device by way of the breathing pressure movement of the pressure chamber.
A switchable shutting device makes it possible to interrupt the respiratory gas supply when the mask is taken off. The shutting device consists of a shaft rotatably mounted in the breathing chamber. One end is passed in an airtight guide bushing through the wall of the breathing chamber to the outside and is provided there with a radial actuating lever. At the lever the shaft can be turned between two end positions. In one end position, the shutting position, an elastic tongue of the actuating lever snaps into a recess in the wall of the breathing chamber. In the shutting position the wire strap touches the lever arm of the inlet valve and brings it into the closing position. A thigh spring pushes the wire strap, which turns with the shaft, into the other end position, the release position, in which it abuts against the inner wall of the breathing chamber and permits free movement of the lever arm. With the mask taken off, the previously actuable actuating lever has been engaged into the shutting position, thereby interrupting the respiratory gas supply. After the mask has been placed on, the first breath causes automatic switching on. With the inhalation suction acting on the membrane a force sufficient to push the shutting device out of the locking engagement of the shutting position must be produced at the lever arm. The thigh spring then brings the shutting device into the release position.
Since, however, the turn-on force depends on the locking of the shutting device present on the outer side, it is possible that in the course of use dirt, the use of force, or wear will cause changes which will affect the switch-on resistance and reliability. Proper sealing of the lead-through through the wall of the breathing chamber is expensive and a possible source of malfunction, as is also the construction of the shutting device from a plurality of separate parts.
Further, German patent application No. P 32 45 717 another respirator mask with positive pressure in the interior of the mask is known which also is created and maintained by a lung controlled valve. The housing of the lung controlled valve with a respiratory gas feed connection and with a discharge connection for the respiratory gas to the mask is closed off with a cover. The housing is separated by a control membrane, forming an outer chamber toward the cover and a breathing chamber therebelow. The breathing chamber is connected with the interior of the mask through the discharge connection. The respiratory gas connection is switchable with the breathing chamber through an inlet valve which is in contact with the control membrane via a lever means.
The outer chamber contains a control means with which, manually released by a shutoff valve to be displaced laterally, the control membrane is held in a shutting position relieved of pressure, through a holding collar with a simultaneous closing of the inlet valve. Upon inhalation, the pressure in the mask and in the breathing chamber decreases. Thereby, under the force of a spring, a positive pressure lever displaces the inlet valve into open position via the control membrane and the lever means. If removal of the mask, and hence also the absence of positive pressure outflow of respiratory gas, is to be prevented, the shutoff valve, now in the shutting position, lifts the pressure lever off the control membrane, which then rises, relieved of pressure, under the action of the closing spring of the valve, which closes. Its holding collar is wedged in after the shutoff valve has been released. The inlet valve remains closed to the next deep breath after the mask has been placed on.
It is the object of the invention to improve a respirator mask with positive pressure in the interior of the mask, in such a way that with the elimination of mechanical parts from the lung controlled valve, wear and possible wedging of a lever mechanism can no longer be a cause of failure.
In accordance with the invention the respirator mask operates with a positive pressure at its interior and for this purpose it has a lung controlled valve having a housing with a breathing gas chamber which discharges before the user's respiratory organs which is connected to a respiratory gas supply through a valve which is regulated by a diaphragm separating the housing and the breathing gas chamber from an outer chamber to regulate the supply of the breathing gas to the mask through the breathing gas chamber. With the invention, a key is mounted on the housing and is movable relative thereto against the force of a return spring and it has an inner end which is magnetically engageable with the diaphragm so as to hold it so that it closes the valve from the breathing gas supply so that there is no outflow of respiratory gas when the mask is removed. The arrangement is such that when the mask is used the key becomes automatically disengaged. The inlet valve with remain closed until the next breath by the user in which case the key will become released from the diaphragm.
An advantage achieved with the invention in particular is that, instead of a plurality of parts which must move together, practically only the magnetic key opposite a steel plate in the control membrane causes the shutting of the inlet valve in any case. The magnetic forces are controllable with certainty and there can be no wear.
Accordingly, it is an object of the invention to provide an improved breathing gas control valve whose housing contains between a breathing chamber discharging for the user's respiratory organs and an outer chamber connected with the outside atmosphere provided with a shutoff means, a control membrane with which an inlet valve for the respiratory gas can be actuated via coupling means and wherein the shutoff means is a magnetic key guided in a housing cover and held externally by a return spring and which carries a magnet at its inner end opposite a steel plate carried on a control membrane which separates the chamber of the valve into an outer chamber and a breathing gas chamber in an arrangement wherein the control diaphragm is connected with the inlet valve via a coupling controlled by a positive pressure spring as a function of the inside pressure of the mask and wherein the pressed in magnetic key keeps the inlet valve closed via the magnetically adhering steel plate.
A further object of the invention is to provide a breathing gas control valve for a breathing mask in which means are provided to ensure the closeoff of the breathing gas when the mask is not used and which is simple in design, rugged in construction and economical to manufacture.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.